So, I was thinking of a slouch hat, decorating with animal teeth, that when worn, makes the wearer feel like they're in a constant state of peril.
Basically, it'd work by introducing hallucinations, and completely redecorating the environment for the user, making them believe they're seeing hazards and wildlife.

I've got a rough bit I was working on, here, but I only want critique for the idea:

SCP-XXXX must be stored safely in a sealed, steel alloy box, complete with coded lock and padlock. The box must then be hidden out of sight, to avoid accidental discovery by those who have previously used it.

Description:

Subject is a slouch hat, originating from ██████, Australia. On first observation the subject appears to be completely normal, but members of staff have described it as ‘cool’ and in most cases express a desire to wear it.
However, when worn, its anomalous qualities are revealed, quickly. The hat seems to have a very powerful effect on its wearer, who become attached to the hat, and will not remove it (Stage I). Further tests show that after Stage I, Stage II will commence, usually between 1-3 hours, and the hat will cause the wearer to experience severe hallucinogenic visions, sounds, and smells and will overtake all senses at this point.

These hallucinations all seem to be of an adventurous nature and 100% of tests show that subjects are envisioning the current area in an entirely different perspective.
The effects of the subject can be measured in stages.

Addendum:

Stage I: Lasts approximately a minute. Wearer will defend the hat until Stage II commences, but forced removal will ensue in the subject attempting to get SCP back, at any cost.

Stage II: Wearer begins to hallucinate, seeing various dangers often associated with stereotypical peril hidden about the vicinity. The victim will also claim that staff and humans nearby are in immediate danger, and will attempt to persuade them to follow, or will dive at them and move them out of the way in order to ‘save’ them. Please note that subjects will begin to craft makeshift weaponry and will, if possible, make temporary shelters and ‘scout’ the area for supplies.

Stage III: The effects will increase in power, and wearers will begin to see other creatures as exaggerated forms, based on their past or genes. This can ensue in violence, often, with the subject believing all entities are hazardous. By this time the effects last much longer when the SCP is removed, and have lasted from 2 weeks to 3 months. Upon seeing another entity wearing the hat, regardless of species, subject will attempt to engage the new wearer, and the two will 99% of the time, end up in conflict over possession of the SCP.